Fluid meter

ABSTRACT

A fluid meter is described having multiple pistons and connecting rods that are connected to the crankshaft by one common crankpin that is radially offset from the crankshaft such that an axis through the endpoints of the yoke slot of one connecting rod forms an angle alpha with the alignment axis of the two axially aligned cylinders, and that an axis through the endpoints of the yoke slot of the other connecting rod forms another, different angle beta with said alignment axis, so that the corresponding pistons reciprocate out of phase.

CLAIM OF PRIORITY

Under 35 U.S.C. §119, this application claims the benefit of a foreignpriority filed in the European Patent Office, serial number 09012702.8,filed Oct. 7, 2009, the entire contents of which are hereby incorporatedby reference.

TECHNICAL FIELD

The present invention relates generally to a fluid meter for volumemeasurement of a flowing fluid. More particularly, the present inventionrelates to a multiple piston type fluid meter.

BACKGROUND ART

Fluid meters are widely used for most kinds of fluids in differentapplication areas. Fluid meters are, for example, used in fueldispensing pumps for retail sale of motor fuel, providing a means formeasuring the quantity dispensed from the pump. The measured volume istypically communicated to a register, displaying the dispensed volumeand the price.

A fluid meter commonly used for fuel dispensers is shown by Ainsworth,U.S. Pat. No. 2,756,726. In this disclosure, a meter having a multiplepiston hydraulic motor is used. Fluid is allowed to enter cylinders andcause reciprocation of the pistons. The pistons are connected to ashaft, that will rotate as an effect of the reciprocation. A rotaryvalve, coupled to the shaft, admits liquid to the cylinders or permitsflow to the outlet connections, in proper timed relation. The fluidmeter utilizes what may be termed “hypothetical” cylinders, mechanicallyand hydraulically cooperating with the cylinders and pistons which arestructurally existent.

This is accomplished by arranging the ports and the rotary valve so asto sequentially admit fluid to both the crankcase and the ends of thecylinders at the same time as fluid is withdrawn from the cylinders. Thefluid volume admitted to, or withdrawn from, the crankcase is thealgebraic sum of the volume withdrawn from, or admitted to, thecylinders. Two pistons, actuated through the valve mechanism,advantageously 120 degrees out of phase, thus perform the workequivalent of three pistons. This reduces the actual number of cylindersrequired for a given capacity, reduces internal friction and pulsation,and achieves smoother operation. The two pistons are attached viaconnecting rods to a crankshaft with a radially offset crank pin. Thecrank pin engages a yoke in each connecting rod so that thereciprocating movement of the two pistons is transformed into a rotarymotion of the crankcase in accordance with the Scotch Yoke typeprinciple. To accomplish the phase differences between the pistons, thetwo physical cylinders are oriented with an angle of 120 degrees betweentheir respective center axis.

The Ainsworth fluid meter has several drawbacks, as e.g., therequirement of special piston guide barrels, the arrangement ofcylinders and guide barrels is difficult to mold or cast and machine,and the register is driven by a shaft extending through the meterhousing with accompanying risk of leakage.

A similar fluid meter is disclosed by Spalding, U.S. Pat. No. 5,686,663and WO 98/49530. This fluid meter aims at eliminating the drawbacks ofthe Ainsworth fluid meter. Thus, the two angled cylinders of Ainsworthare aligned along a common center axis to eliminate the bulkyconstruction of Ainsworth. To accomplish the same piston reciprocity,the crankshaft is modified with an extra crank arm. The in-lineconstruction is advantageous when several meters have to be mounted inone dispenser, which is the normal case in most modern fuel dispensers.

The Spalding fluid meter, however, is not without some drawbacks. Toachieve the correct phase difference between the operation of thecylinders, the crankshaft requires a complicated structure with twocrank arms and two crank pins. This complex construction is complicatedto manufacture and thus expensive. The angle between the crank arms iscrucial, which further complicates the manufacturing process. Since thecrankshaft has many parts, as a result of the necessity of two crankarms, the crankshaft will also be less robust with increased risk ofdamage and resulting service.

SUMMARY OF THE INVENTION

According to one or more embodiments disclosed herein, a fluid metercomprises a housing defining at least one crankcase and twoaxially-aligned cylinders, a crankshaft disposed in the crankcase, twopistons respectively mounted in the cylinders for reciprocal movement, afirst connecting rod connected to one of the pistons and to thecrankshaft for rotating the crankshaft in response to the movement ofthe one piston, and a second connecting rod connected to the otherpiston and to the crankshaft for rotating the crankshaft in response tothe movement of the other piston, wherein the first and secondconnecting rods have yoke slots for receiving a crank pin. One or moreembodiments of the fluid meter is characterized in that the connectingrods are connected to the crankshaft by one common crank pin that isradially offset from the crankshaft; that an axis through the endpointsof the yoke slot of one connecting rod forms an angle alpha with thealignment axis of the two axially aligned cylinders; and that an axisthrough the endpoints of the yoke slot of the other connecting rod formsanother, different angle beta with said alignment axis, so that thecorresponding pistons reciprocate out of phase.

Using yoke slots that extend along a straight line between the endpointsof the yoke slot is a relatively easy way to generate piston movementwith a motion speed following a harmonic sinus shape. It should howeverbe noted that other shapes of the yoke slots could be used, e.g. wherethe yoke is bent along a suitable curve. The design of the inlet/outletvalve of the fluid meter casing could, e.g., require a specialreciprocating piston movement, invoked by the yoke slots, to match itsdesign.

The settings of the yoke slots may be arranged so as to cause thepistons to reciprocate out of phase even though the cylinders arealigned along the same center axis. Using the yoke slots according toone or more embodiments disclosed herein, only one crank arm isnecessary to achieve piston movements that are out of phase. One or morebenefits may result from using only one crank arm for the movement ofthe pistons. The number of components may be reduced, leading to reducedmaterial costs. The manufacturing procedure may be simplified, leadingto cheaper production costs. One single crank arm instead of twotypically leads to a crankshaft assembly that is a more robust and rigidunit. Further, the problem of providing the correct angle between twocrank arms is eliminated as there is only one crank arm.

It is it is preferred that each one of the yoke slots of said twoconnecting rods is adapted to extend along a straight line between saidendpoints. As mentioned above, this is the easiest way to generatepiston movement with a motion speed following a harmonic sinus shape andis therefore preferred at present.

Preferably, the angles alpha and beta are chosen so that the pistonsreciprocate approximately 60° out of phase.

It is advantageous that the yokes reciprocate approximately 60° out ofphase to achieve a smooth operation of the fluid meter. To be able toconstruct the housing in a simple and fairly symmetric manner, a phasingof the pistons 60° out of phase together with a proper inlet/outletvalve design and a geometry where the cylinders are directed from eachother, i.e. 180° angled from one another, will allow the fluid flow toenter and exit the two cylinders and the “hypothetical” cylinder in thecrankcase, i.e. in between the reciprocating pistons, one by one in asmooth motion with a phase offset by 120° between the operation of thecylinders.

It is also preferred that the angle alpha of the yoke slots of the fluidmeter is less than 90° and the angle beta is more than 90°. Morepreferably, alpha is approximately 60° and beta is approximately 120°.The latter angle setting will cause the pistons to reciprocate 60° outof phase and the operation of the cylinders will thus be 120° out ofphase, as preferred, due to the 180° angle between the two physicallyexisting cylinders.

Another advantage that may result from using oblique settings of theyoke slots, preferably with angles as described above, is thatmanufacturing of the fluid meter is simplified. Not only may thecrankshaft be simpler, having only one crank arm and one crank pin, butthe setting of the angles creating the out-of-phase piston movementswill be made in the manufacturing process of the yoke slots instead ofin the mounting of two crank arms on the crankshaft. Accurate andprecise formation of the yoke slots is fairly simple to achieve. Theyokes and slots can be manufactured by moulding, punching a metal sheet,cutting etc. All of these methods are simple and they do not differ fromthe way other yokes are manufactured. This means that the manufacturingchanges in the production of the yokes that are invoked by the presentdisclosure will be very small.

In one or more embodiments, it is preferred that a portion of oneconnecting rod engage the other connecting rod to support and guide theother connecting rod during movement. This can, e.g., be achievedthrough each connecting rod having a pair of guide tabs engaging theopposed side edge portions of the other connecting rod. The guide tabscould further have notches for respectively receiving the opposed sideedge portions.

To guide the connecting rods in the manner described with respect tocertain embodiments has the advantage of ensuring that the rods move inparallel to each other without deviation from the center axis of thecylinder. It is further not necessary to have yokes that extend in thefull width of the cylinder, when guiding the connecting rods in oneanother. Such yokes with reduced width typically lead to reduction oravoidance of friction to the cylinder walls, which is advantageous notonly for simplifying the operation of the connecting rods and theirrespective yokes, but also to reduce damages to the cylinder walls. Ifthe walls are scratched or damaged in any way by the yokes, the pistonring gaskets will eventually not be able to seal the cylinders from thecrank case as needed.

In one or more embodiments, it is further preferred to provide a fluidmeter of the above type where ports are defined in the housing incommunication with the cylinders and the crankcase, and furthercomprising a port valve mounted on the crankshaft for rotation therewithand having a plurality of ports for sequentially registering with theports in the housing for distributing fluid into and from the cylindersand the crankcase to control the movement of the pistons. The port valveas described above will ensure relatively precise volume flow throughthe cylinders of the fluid meter.

In one or more embodiments, the fluid meter preferably comprises atleast one wheel coupled to the crankshaft and has at least one magneticpole, and at least one sensor to detect the influence of the at leastone magnetic pole and to generate a signal corresponding to the flow ofthe fluid into and from the corresponding cylinders and the crankcase.

One or more embodiments of the present disclosure provides a multiplefluid meter assembly comprising at least two fluid meters of the abovetype. Such an assembly will provide a compact design when multiple fluidmeters are required.

In certain embodiments, the at least two fluid meters are preferablyarranged such that their alignment axes are parallel. An assembly withparallel fluid meters will provide a meter assembly that is verycompact. This is often an important criteria in modern fluid dispensers,where many fluid meters are required and the fluid dispenser unit designrequires the internal equipment to be small.

It may also be preferred that the fluid inlet and the fluid outlet ofone fluid meter communicate with the fluid inlet and the fluid outlet ofanother fluid meter, respectively, so as to connect the individual fluidmeters in parallel.

According to one or more embodiments, the present disclosure provides afuel dispensing unit for refuelling vehicles, comprising a fluid meteror a multiple fluid meter assembly of the types described above. Thefluid meter or fluid meter assembly according to the present inventionis especially suitable for fuel dispensers due to its reliability andaccurate measurement capabilities.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, as well as additional objects, features andadvantages of the present invention, will be more fully appreciated byreference to the following illustrative and non-limiting detaileddescription of certain embodiments of the present invention, when takenin conjunction with the accompanying drawings, wherein:

FIG. 1 a is an exploded diagram of connecting rods having slotted yokesand a crankshaft having two crank arms of a fluid meter according to theprior art.

FIG. 1 b is a perspective view of a mounted assembly of the prior art ofFIG. 1 a.

FIG. 2 a is an exploded diagram of connecting rods, a crankshaft havingone crank arm, a rotating valve, a magnetic wheel and a transduceraccording to one embodiment of a fluid meter disclosed herein.

FIG. 2 b is a perspective view of a mounted assembly of FIG. 2 a.

FIG. 2 c is a perspective view of a mounted assembly of FIG. 2 a showingan embodiment of the connecting rods where these are coupled to eachother.

FIG. 3 is a cross sectional view of the fluid meter taken along the axisof the aligned cylinders, corresponding to the line III of FIG. 2 b.

FIG. 4 is a cross sectional view along the line IV in FIG. 3 of thefluid meter according to the invention.

FIG. 5 a is a top view of the rotary valve of the fluid meter.

FIG. 5 b is a cross sectional view of the rotary valve of the fluidmeter.

FIG. 6 is a plan view showing the ports of a rotary valve superimposedover a valve seat of the fluid meter in FIG. 3.

FIG. 7 is an isometric view of a unitary assembly incorporating twofluid meters similar to the meter of FIGS. 1-6.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

FIGS. 1 a and 1 b shows a pair of connecting rods, 1, 2, according toprior art (U.S. Pat. No. 5,686,663 to Spalding et al), each connected toa piston, 3, 4, as described in the prior art. The connecting rods, 1,2, have Scotch yoke portions, 5, 6, with oblong yoke slots, 7, 8. Thecenter axes of the yoke slots are perpendicular to the center axes ofthe connecting rods, 1, 2. To move the connecting rods, 1, 2, and thusalso the pistons, 3, 4, with a phase difference of 60°, as described inthe prior art of Spalding, the yoke portions, 5, 6, will have to bedriven by different crank arms, 9, 10, of the crankshaft, 11 as depictedin FIGS. 1 a and 1 b.

FIGS. 2 a and 2 b show the connecting rods 12, 13 of one embodiment ofthe present invention, the connecting rods 12, 13, having yoke portions14, 15, with yoke slots 16, 17. To perform a reciprocating movement ofthe pistons, 3, 4, using only one crank arm, 18, the center axes of theoblong yokes slots, 16, 17, are each angled 30° compared to theperpendicular direction to the center axes of the connecting rods 1, 2.The combined angle between the center axes of the oblong yoke slots ofthe two connecting rods, 12, 13, is thus 60°. This arrangement of theyoke slots will invoke the same movement of the connecting rods, 12, 13,and thus also the pistons, 3, 4, as the prior art, i.e. a reciprocatingmovement of the pistons 60° out of phase, but with the use of only onecrank arm, 18, and one crank pin, 19.

FIG. 2 c shows another embodiment of the connecting rods, 12, 13. Aportion 20 of one connecting rod, 12, engages the other connecting rod,13, to support and guide the other connecting rod, 13 during movement.Each connecting rod, 12, 13, further has a pair of guide tabs, 21, 22,engaging the opposed side edge portions, 23, 24, of the other connectingrod, 12, 13. Notches are further formed in the guide tabs, 21, 22,respectively for receiving the opposed side edge portions, 23, 24. Bycoupling the connecting rods, 12, 13, the connecting rods, 12, 13, arelimited to a movement along the center axis of the aligned cylinders,25, 26. It should, however, be noted that the effect of the connectionof the connecting rods, 12, 13, limiting the movement of the connectingrods, 12, 13, could be made in a number of different ways. The rodscould e.g. be guided by guiding rails mounted to the cylinder walls,limiting the movement reciprocating along the cylinder center axes. Thesame effect could also be achieved by using connecting rods, 12, 13,having any other coupling means to each other or to the cylinders, 25,26 to limit their movement as described.

The connecting rods, 12, 13, of FIG. 2 c are in this embodiment formedfrom metal sheet with yoke portions, 23, 24, which are punched toprovide first and second slotted yokes, 25, 26. The connecting rods, 12,13, could, however be made from any other suitable material.

In FIG. 3 the reference numeral 27 designates a flow meter embodimentaccording to the present disclosure. The flow meter 27 includes a flowmeter body 28 having a crankcase portion 29 (indicated by the brokenlines) and opposing, axially aligned, first and second cylinderportions, 25 and 26, respectively, extending outwardly from thecrankcase (from the broken lines). The head ends of the cylinderportions 25 and 26 are capped by first and second head end cover plates30 and 31, respectively.

A magnetic wheel 32 is connected to the crankshaft 11 at the center ofthe magnetic wheel 32. A series of magnetic poles (not shown) areincorporated in the magnetic wheel 32 angularly spaced about the outercircumference of the wheel 32.

A Hall effect transducer 33 having two sensors, well known in the art,is mounted within close proximity to the magnetic wheel 32. Due to theproximity of the sensors to the wheel 32, the sensors can detectfluctuations in the magnetic influence of the magnetic poles of thewheel 32 when the wheel 32 rotates. In response to such detection, thetransducer 33 generates a pulsed signal proportional to the rate ofrotation of the wheel 32. The two sensors are, furthermore, horizontallyspaced so that the direction of rotation of the magnetic wheel 32 can bedetermined by identifying which of the two sensors first detects themagnetic influence of a particular pole.

A ball bearing assembly 34 is fitted in a small bore 35 in the meterbody 28. A crankshaft 11 is rotatably disposed in the bearing assembly34. The crankshaft 11 has a vertical orientation bearing laterallyagainst the bearing assembly 34. The upper portion of the crankshaft 11extends above the bearing assembly 34 and is shaped to receive a rotaryvalve more thoroughly discussed with reference to FIGS. 5 and 6 below. Acrank arm 18 is connected to the lower portion of the crankshaft 11 andextends radially outwardly from the crankshaft. A crankpin 19 extendsdownwardly from the radially outer part of the crank arm 18 through afirst roller bearing 36 and a second roller bearing 37, the secondroller bearing 37 being located below the first roller bearing 36.

Referring to FIG. 3, the flow meter 27, as shown, further includes firstand second pistons 3, 4, disposed in the cylinders 25 and 26,respectively. First and second connecting rods, 12, 13, drivinglyconnect the respective pistons 19, 20, to the respective first andsecond roller bearings, 36, 37. The connecting rods 12, 13 are henceconnected to the crankshaft via the roller bearings, 36, 37. Theconnecting rods 12, 13 are more clearly shown in FIGS. 2 a and 2 b. Thefirst and second connecting rods, 12, 13 are in this particularembodiment formed from metal sheet with yokes portions, 14, 15, whichare punched to provide first and second oblong slotted yokes, 16, 17 forslidingly engaging the respective first and second roller bearings, 36,37. The oblong slotted yokes, 16, 17 do in this embodiment have straightcentral axes with an angle of 60° between the respective center axis.The first and second slotted yokes 16, 17, have center axes with anglesof 120° and 60°, respectively, to the center axis of the axially alignedfirst and second cylinder portions 25 and 26.

Referring to FIG. 3, the pistons 3, 4, have circular recesses, 38, 39,for receiving gaskets (not shown). The gaskets are made of a resilientmaterial to seal the cylinder head chambers 40 and 41 from the crankcasechamber 42 defined by the crankcase portion 29 and the parts of thecylinder portions 25, 26 that are on the inner sides (facing thecrankcase) of the pistons 3 and 4. The two pistons 3, 4, thus divide thecylinder volumes combined with the crank case portion volume into threechambers, sealed from each other, the head chambers 40, 41 and thecrankcase chamber 42.

FIG. 6 shows the valve seat 43 as seen from the top of the flow meter 27of FIG. 3. The valve seat 43 includes first, second and third arcuateports, 44, 45, 46, which each cover an arc about the crankshaft bore 47of approximately 80° and are angularly spaced apart approximately 40°between ports. Referring to both FIGS. 3 and 6 the first port 44 is influid communication with the first head end chamber 40 via a firstpassageway 48 formed in the fluid meter body 28. The second port 45 isin fluid communication with the second head end chamber 41 via a secondpassageway 49 formed in the fluid meter body 28. Referring to FIGS. 6and 4, the third port 46 is in fluid communication with the crankcasechamber 42 via a third passageway 50 formed in the fluid meter body 28.

Referring to FIG. 5 a, a rotary valve 51 is positioned on top of thevalve seat 43 to control the admission and discharge of a fluid into andout of the first, second, and third ports 44, 45, 46. The rotary valve51, with reference to FIGS. 5 a and 5 b, includes a hole 52 formed inthe center thereof through which the crankshaft 11 extends for rotatablycoupling the valve 51 to the crankshaft 11. Referring to FIGS. 5 a, 5 band 6, the rotary valve 51 further includes an arcuate inlet port 53 andan arcuate outlet port 54 axially and radially aligned to alternatelyregister with the first, second, and third arcuate ports 44, 45, 46 ofthe valve seat 43 when the valve 51 is rotated by the crankshaft 11. Theports 53, 54 each cover an arc about the hole 52 of approximately 100°and are angularly spaced apart approximately 80° between ports.

As further shown in FIGS. 3 and 4, a mounting flange (or meter dome) 55is secured to the top of the flow meter body 28. A supply chamber 56 isformed in the flange for supplying fluid to the inlet port 53 of therotary valve 51. A supply port 57 formed in the flange provides fluidcommunication between the supply chamber 56 and fluid supply lines (notshown). Similarly, an annular discharge chamber 58 is formed in theflange 55 for receiving fluid discharged from the outlet port 54 of therotary valve 51. A discharge port 59 provides fluid communicationbetween the discharge chamber 58 and fluid discharge lines (not shown).

FIG. 6 further depicts one instantaneous position of the rotary valveports 53, 54 (shown in phantom) superimposed over the first, second, andthird ports 44, 45, 46 of the valve seat 43. In operation, the rotaryvalve 51 is rotated by the crankshaft 11 in a counterclockwise directionas indicated by the arrow 60. Accordingly, the inlet and outlet ports53, 54 sequentially register with each of the ports 44, 45, 46. As shownin FIG. 6, the inlet port 53 is registered with the third port 46 andthe outlet port 54 is registered with the second port 45. Registrationof the inlet port 53 with the first port 44 is depicted as impending.Because each of the ports 44, 45, 46 cover an angle of approximately 80°and each of the rotary valve ports 53, 54 cover an angle ofapproximately 100°, each port 44, 45, 46 alternately registers with theinlet port 53 for 180° of rotation of the crankshaft 1 and then with theoutlet port 54 for 180° of rotation. It can be appreciated that theinlet port 53 or the outlet port 54 may register with one or two, butnot all three, of the ports 44, 45, 46 simultaneously. The ports 44, 45,46 may, however, register with only one of the ports 53, 54 at a time.

To more fully illustrate the operation of the flow meter 27, and withreference to FIG. 3, it will be assumed that, initially, the flow meterbody 28 is filled with fluid, the crankshaft 11 is rotated to place thefirst piston 3 in as close proximity to the head cover 30 as possible(i.e., a “top dead center” position), the second piston 4 leads thefirst piston 3 by a phase angle of 60°, and the rotary valve ports 53,54 are related to the first, second, and third ports 44, 45, 46 as shownin FIG. 6 a fluid, such as gasoline from an external source (not shown),is then supplied through the supply port 57 and passed through thesupply chamber 56, the inlet port 53 of the rotary valve 51, and, inaccordance with FIG. 6, through the third port 46. The fluid then flowsthrough the third passageway 50 (FIG. 4) and into the crankcase chamber42 where it applies pressure to displace the second piston 4 outwardly(away from the crankshaft 11). The first piston 3 resists outwardmovement since it is in a top dead center position. The outward movementof the second piston 4 expels fluid from the second chamber 41 therebycausing the fluid to pass through the second passageway 49, the outletport 54 of the rotary valve 51, the discharge chamber 58, and outthrough the discharge port to 59 to a discharge line (not shown). Themovement of the second piston 4 also drives the crankshaft 11 via thesecond connecting rod 13. Accordingly, the crankshaft 11 imparts counterclockwise rotation to the rotary valve 51 and the inlet port 53 beginsto register with the first port 44. Fluid in the supply chamber 48 thenbegins to flow through the inlet port 53 of the rotary valve 51 andthrough the first port 44. The fluid then flows through the firstpassageway 48 into the first chamber 40 and applies pressure to displacethe first piston 3 inwardly (towards the crankshaft 11), therebyeffecting further rotation of the crankshaft 11 and the rotary valve 51.The process continues according the principles described herein. As aresult, the pistons 3, 4 reciprocate in the cylinders 25, 26,respectively, thereby rotating the crankshaft 11, the attached rotaryvalve 51, and the magnetic wheel 32. The sensors in the Hall effecttransducer 33 detect the consequent fluctuation in the magneticinfluence of the magnetic poles on the wheel 32 and generate a pulsedsignal which is proportional to the flow rate of the fluid passingthrough the flow meter 27. Although not clear from the drawings, it isunderstood that the pulsed signal may be employed to drive an electroniccounter and indicator for recording the volume and total value of fluid,such as gasoline, dispensed through the flow meter 27.

The inlet and outlet ports 53, 54 of the rotary valve 51 and the ports44, 45, 46 cooperate such that the volume of fluid admitted to, orwithdrawn from, the crankcase chamber 42 is equal to the algebraic sumof the volume respectively withdrawn from, or admitted to, the head endchambers 40, 41. Thus the crankcase chamber 42 provides what may betermed a “blind” or “hypothetical” piston and cylinder, mechanically andhydraulically cooperating with the pistons 3, 4 which are structurallyexistent. Thus, the meter operates hydraulically and mechanically like athree piston meter or hydraulic motor although it only has the physicalcomponents of a two piston meter or motor. It should be noted that theflow into and out of the flow meter 27 is substantially constant. Thisconstant flow results from reciprocating the axially-aligned pistons 3,4 60° out of phase and from utilizing yokes 16, 17 as described above,which are substantially harmonic in conformity with Scotch Yokes.

Thus, as a result of all of the foregoing, the disclosed fluid meter maybe compact, yet cost-efficient and mechanically efficient.

It is understood that the yoke slots could have other shapes. The yokescould, e.g., be curved to accomplish a perfect sine function movement orany modification of a periodic sine function.

It is further understood that multiple flow meters 27 may be integratedinto a single assembly to gain several advantages over the single flowmeter described hereinabove. For example, a duplex flow meter assembly61 wherein two fluid meters 27, as depicted in FIG. 7, are integratedtogether, would facilitate the construction of gasoline dispenser pumpstations having two, four, six, or eight gasoline dispensers.Furthermore, a duplex flow meter 61 would only require a single meterbody, meter dome, and end cover, thereby economizing on manufacturingcosts. Installation of duplex flow meters 61 is facilitated as a resultof simplified mounting and pipe work and the reduced cabinet sizerequired to house a duplex fluid meter. Flexibility is also enhancedbecause a duplex flow meter could also serve a single hose outlet attwice the speed of delivery of a single unit flow meter.

It is further understood that the ports 44, 45, 46, 53, 54 may coverarcs of a number of different angles and, moreover, may have non-arcuateshapes.

It is still further understood that the supply port and the dischargeport may instead be utilized as discharge and supply ports respectively.Furthermore, the supply and discharge lines connected thereto may bearranged for measuring the volume of any fluid that flows through anyline. For example, in addition to measuring a fluid, such as gasoline,that flows from a dispenser, the meter could be used to measure thevolume of water flowing from a pipe into a structure such as aresidential house or other building.

It is understood that other variations in the present invention arecontemplated and in some instances, some features of the invention canbe employed without a corresponding use of other features. Accordingly,it is appropriate that the appended claims be construed broadly in amanner consistent with the scope of the invention.

1. A fluid meter comprising: a housing defining at least one crankcaseand two axially-aligned cylinders, a crankshaft disposed in thecrankcase, two pistons respectively mounted in the cylinders forreciprocal movement, a first connecting rod connected to one of thepistons and to the crankshaft for rotating the crankshaft in response tothe movement of the one piston, and a second connecting rod connected tothe other piston and to the crankshaft for rotating the crankshaft inresponse to the movement of the other piston, the first and secondconnecting rods having yoke slots for receiving a crank pin theconnecting rods being connected to the crankshaft by one common crankpin that is radially offset from the crankshaft, the fluid meter beingarranged such that an axis through the endpoints of the yoke slot of oneconnecting rod forms an angle alpha with the alignment axis of the twoaxially aligned cylinders, and an axis through the endpoints of the yokeslot of the other connecting rod forms another, different angle betawith said alignment axis, so that the corresponding pistons reciprocateout of phase.
 2. A fluid meter according to claim 1, wherein each one ofthe yoke slots of said two connecting rods is adapted to extend along astraight line between said endpoints.
 3. A fluid meter according toclaim 1, wherein said angles alpha and beta are chosen so that thepistons reciprocate approximately 60° out of phase.
 4. A fluid meteraccording to claim 1, wherein alpha is less than 90° and beta is morethan 90°.
 5. A fluid meter according to claim 1, wherein alpha isapproximately 60° and beta is approximately 120°.
 6. A fluid meteraccording to claim 1, wherein a portion of one connecting rod engagesthe other connecting rod to support and guide the other connecting rodduring movement.
 7. A fluid meter according to claim 6 wherein eachconnecting rod has a pair of guide tabs engaging the opposed side edgeportions of the other connecting rod.
 8. A fluid meter according toclaim 7 wherein notches are formed in the guide tabs for respectivelyreceiving the opposed side edge portions.
 9. A fluid meter according toclaim 1, wherein ports are defined in the housing in communication withthe cylinders and the crankcase, and further comprising a port valvemounted on the crankshaft for rotation therewith and having a pluralityof ports for sequentially registering with the ports in the housing fordistributing fluid into and from the cylinders and the crankcase tocontrol the movement of the pistons.
 10. A fluid meter according toclaim 1, further comprising at least one wheel coupled to the crankshaftand having at least one magnetic pole, and at least one sensor to detectthe influence of the at least one magnetic pole and to generate a signalcorresponding to the flow of the fluid into and from the correspondingcylinders and the crankcase.
 11. A multiple fluid meter assemblycomprising at least two fluid meters, each fluid meter comprising ahousing defining at least one crankcase and two axially-alignedcylinders, a crankshaft disposed in the crankcase, two pistonsrespectively mounted in the cylinders for reciprocal movement, a firstconnecting rod connected to one of the pistons and to the crankshaft forrotating the crankshaft in response to the movement of the one piston,and a second connecting rod connected to the other piston and to thecrankshaft for rotating the crankshaft in response to the movement ofthe other piston, the first and second connecting rods having yoke slotsfor receiving a crank pin the connecting rods being connected to thecrankshaft by one common crank pin that is radially offset from thecrankshaft, the fluid meter being arranged such that an axis through theendpoints of the yoke slot of one connecting rod forms an angle alphawith the alignment axis of the two axially aligned cylinders, and anaxis through the endpoints of the yoke slot of the other connecting rodforms another, different angle beta with said alignment axis, so thatthe corresponding pistons reciprocate out of phase.
 12. A multiple fluidmeter assembly according to claim 11, wherein the at least two fluidmeters are arranged such that their alignment axes are parallel.
 13. Amultiple fluid meter assembly according to claim 11, wherein the fluidinlet and the fluid outlet of one fluid meter communicate with the fluidinlet and the fluid outlet of another fluid meter, respectively, so asto connect the individual fluid meters in parallel.
 14. A multiple fluidmeter assembly according to claim 12, wherein the fluid inlet and thefluid outlet of one fluid meter communicate with the fluid inlet and thefluid outlet of another fluid meter, respectively, so as to connect theindividual fluid meters in parallel.
 15. A fuel dispenser comprising: anozzle for dispensing fuel, a display, a fluid meter comprising: ahousing defining at least one crankcase and two axially-alignedcylinders, a crankshaft disposed in the crankcase, two pistonsrespectively mounted in the cylinders for reciprocal movement, a firstconnecting rod connected to one of the pistons and to the crankshaft forrotating the crankshaft in response to the movement of the one piston,and a second connecting rod connected to the other piston and to thecrankshaft for rotating the crankshaft in response to the movement ofthe other piston, the first and second connecting rods having yoke slotsfor receiving a crank pin the connecting rods being connected to thecrankshaft by one common crank pin that is radially offset from thecrankshaft, the fluid meter being arranged such that an axis through theendpoints of the yoke slot of one connecting rod forms an angle alphawith the alignment axis of the two axially aligned cylinders, and anaxis through the endpoints of the yoke slot of the other connecting rodforms another, different angle beta with said alignment axis, so thatthe corresponding pistons reciprocate out of phase.
 16. A fuel dispenseraccording to claim 15, wherein each one of the yoke slots of said twoconnecting rods is adapted to extend along a straight line between saidendpoints.
 17. A fuel dispenser according to claim 15, wherein saidangles alpha and beta are chosen so that the pistons reciprocateapproximately 60° out of phase.
 18. A fuel dispenser according to claim15, wherein a portion of one connecting rod engages the other connectingrod to support and guide the other connecting rod during movement.
 19. Afuel dispenser according to claim 15, wherein ports are defined in thehousing in communication with the cylinders and the crankcase, andfurther comprising a port valve mounted on the crankshaft for rotationtherewith and having a plurality of ports for sequentially registeringwith the ports in the housing for distributing fluid into and from thecylinders and the crankcase to control the movement of the pistons.